The mean transit time and functional image in asialoglycoprotein receptor scintigraphy: a novel modality for evaluating the regional dynamic function of hepatocytes.

UNLABELLED: In this study, we attempted to evaluate the regional dynamic function of hepatocytes by introducing unique parameters in (99m)Tc-diethylenetriaminepentaacetic acid-galactosyl-human serum albumin (99m)Tc-GSA) scintigraphy. (99m)Tc-GSA scintigraphy provides valuable information for the receptor population density. However, the conventional indices are the results of the analyses of 2 fixed points and, as a result, it is not possible to accurately estimate the regional dynamic function. METHODS: We performed (99m)Tc-GSA scintigraphy 100 times on a total of 54 pediatric patients. The average age at examination was 7.4 +/- 5.8 y. Ninety-one of the 100 scintigraphy cases were available for this study. We converted the time-activity curve for the liver of (99m)Tc-GSA to a horizontal mirror image curve, and, on the basis of the height-over-area method, calculated the mean transit time (MTT) in each pixel and depicted the functional image as unique parameters, which were thus compared with the conventional indices. For these parameters, we used the time-activity curve for only the liver. RESULTS: The whole liver MTT showed a significant correlation with both the clearance (y = 590.3x + 10.3; r = 0.51; P < 0.0001) and the receptor (y = -1,836.2x + 2,038.8; r = -0.66; P < 0.0001) indices. On the basis of the MTT in each pixel, we could depict the functional image of the liver. In actual clinical situations, the functional image was quite useful for making a visual evaluation of the dynamic distribution of (99m)Tc-GSA. The functional image indicated that, even at an extremely early stage of biliary atresia, the hepatic functional reserve might be exacerbated earlier in the right lobe than in the left lobe. CONCLUSION: The MTT and the functional image enable us to elucidate the regional dynamic function of hepatocytes both quantitatively and visually. In addition, this diagnostic modality can be used at virtually all medical institutions using a modified analytic program already in public use.